Question

PLEASE HELP!
for what part of the interval [-pi, pi] is y= -2sinx decreasing??
a. [-pi/2, pi/2]
b. [-pi/3, pi/3]
c. [-pi/4, pi/4]
d. [-pi, 0]
e. [-pi, pi]
PLEASE SHOW ALL STEPS! THANK YOU :)

Answer 1

(a)

Answer 2

dy/dx=-2cos(x), solve for -2cos(x)<0, this occurs between -pi/2 and pi/2 (only where cos(x) is positive